1. Field
This invention is in the field of footwear incorporating resilient apparatus for the purposes of (1) relieving and/or absorbing shock loads resulting from use of the footwear and (2) increasing the endurance of users of such footwear. More specifically it is in the field of such footwear incorporating springs in the soles of the footwear and still more specifically a spring positioned under the ball of the foot of a wearer and another positioned under the heel.
2. Prior Art
More than forty patents in the field have been examined by the inventors of the subject concept and many more patents, not reviewed by the inventors, are cited as references on the patents examined. Further, it is recognized that the examined and cited patents represent only a portion of the prior art in this field, dating back into the late 1890s. Of this prior art, U.S. Pat. No. 741,012, British Patent 1300 and Italian 284,482 are considered most pertinent to the subject application. Also U.S. patent application Ser. No. 217,769, Spring For Floors and the Like is definitely relevant prior art.
In spite of the profuse prior art, a clear need remains for better solutions to the problems addressed by the prior art and much effort is being made to find those solutions. The need remains for footwear which (1) significatly relieves (as different from absorbs) the shock loads encountered by users of the footwear and (2) reduces the effort required from a user of the footwear in specific activities such as hiking, aerobic exercise and sports activities such as basketball and track events. It is now well known in the art that for footwear to best meet the needs cited, the characteristics of the footwear must be attuned to the weight of the user and to the nature of the use. It is also well established that commercial success of such footwear requires that it be economical to manufacture as well as readily attunable to the weight of the user and the nature of the use. Also, it is established that the footwear must be within specific weight limits in order to best meet the needs cited, the weight being one factor to be attuned to the weight of the user.
Therefore the prime objective of the subject invention is provision of footwear which relieves shock loads experienced by the wearer. A second objective is that the footwear not significantly affect the energy required of the wearer in undertaking specific activities. A third objective is that the cost of the footwear not be unduly increased by the incorporation of the features needed to meet the first and second objectives. A fourth object is that the footwear be readily attunable to the characteristics of both the wearer of the footwear and the intended primary activity of the wearer. A fifth objective is that the footwear be clearly within the weight ranges known to be acceptable relative to the combined characteristics of the wearer and the primary intended use of the footwear.